The present invention relates in general to a system for identifying an object that includes a marker, where the system includes a source of irradiance and a detector of light emitted from the marker. More particularly, the present invention relates to the use of a matte material to within the marker or behind the marker to reduce the noise detected by the detector.
Disk drives for receiving removable disk cartridges must have some mechanism for detecting the insertion or presence of a disk cartridge in the drive. The actuator that carries the recording heads of the disk drive across the recording surfaces of the disk should not be allowed to move unless the presence of an appropriate disk cartridge which is non-drive damaging is detected. The removability feature requires that the disk drive have a cartridge insertion opening into which foreign objects can be inserted. If these objects physically engage the drive as a legitimate cartridge would, then the heads could be loaded onto or into the foreign object, thereby destroying the drive. Also, the spindle motor of the disk drive will be activated by a falsely detected foreign object, thereby generating particle debris. In the prior art, mechanical switches are typically employed to detect the presence of a disk cartridge within the drive. Such switches are typically positioned such that when a disk cartridge is inserted fully into the drive, the cartridge contacts the switch, thereby providing an indication that the disk cartridge is present.
The ability to discriminate between cartridge types after insertion into a data storage device but prior to putting the read/write heads on the recording media is of significant value and utility. Principally, this utility comes from the ability to detect the difference between various capacities or generations of data storage cartridges in a downward media compatible data storage drive. This discrimination capability allows for drive/media specific adjustments to be made such as media rotation rate, data channel rates, location of Z track for initial seeking, or even mechanical adjustment in the drive like the active engagement of new crash stop locations. The ability of a disk drive to predetermine the type/generation of data storage cartridge inserted into it prior to enabling the spin-up and engagement of read/write elements also provides the drive system designer with new possibilities for cross-platform interchangeability.
xe2x80x9cRetroreflective Marker For Data Storage Cartridgexe2x80x9d, U.S. Pat. No. 5,638,228, to Thomas, III, describes the reflection of a highly concentrated quasi circular lobe of light whose spread on reflection is captured by the aperture of a phototransistor in close proximity to a light emitting diode (LED). This emitter/detector pair is in the drive and a retroreflective array is on the cartridge. The desired light lobe size is provided by the geometric size of the retroreflector array elements relative to the spacing of the emitter and the detector in the drive. Due to this physical size matching and the fact that retroreflectors are used, this marker on the cartridge is quite insensitive to cartridge tilt and distance from the emitter/detector pair in the drive. This patent is incorporated herein by reference.
As disk storage products become smaller and smaller, the need for a cartridge marker of thinner physical size is required. In very thin disk drives where the distance between the cartridge marker or tag and the optical sensing device is very small (e.g., 1 mm), the inherent reflective gain mechanism obtained with a retroreflector over a diffuse or specular reflector is lost. Holographic directional light control is possible, but due to the very small working distances, the ability for false engagement of the drive is significantly increased with that approach.
xe2x80x9cLatent Illuminance Discrimination Marker System For Data Storage Cartridgexe2x80x9d, U.S. patent application Ser. No. 08/936,970, filed Sep. 26, 1997 (attorney docket no. IOM-9599), now U.S. Pat. No. 6,091,563 to Thomas, III, incorporated herein by reference, describes the use of a latent illuminance marker to identify an object such as a data storage cartridge. A charging light is applied to a latent illuminance marker, comprising a phosphor for example, the charging light is turned off, and the emitted light is detected by a detector such as a phototransistor. Characteristics of the emitted light are used to identify the data storage cartridge. The signal of the emitted light is usually quite faint and is typically amplified or increased. However, amplifying the signal does not increase the discrimination ratio because all signals are amplified by the same amount. The discrimination ratio (i.e., the ratio of the desired and the undesired signals) quantifies how robustly the system operates.
Typically, the latent illuminance material is charged by a light source, such as an LED having a wavelength close to that of the light that is emitted by the latent illuminance material. For example, the charging LED may have a wavelength of about 650 nm (i.e., the latent illuminance material is charged by light having a wavelength of about 650 nm), and the latent illuminance material may emit light having wavelengths between about 750 nm and 1075 nm. In this manner, the signal detected by the detector of emitted light may be polluted by any charging light that is reflected within the system, thereby leading to increased noise in the system and an overall decrease of system performance.
Although the art of detecting and discriminating between data storage cartridges is well developed, there remain some problems inherent in this technology, particularly when the charging light has a wavelength close to the wavelength of the light emitted by the marker. Therefore, a need exists for a tag that produces reliable detection and discrimination between data storage cartridges when the charging light has a wavelength close to the wavelength of the light emitted by the marker.
The present invention is directed to a cartridge for a data storage drive which has a source of irradiance at an irradiance wavelength and a detector of irradiance for determining whether the cartridge is suitable for use in the drive. The cartridge comprises a body; a data storage medium in the body; a marker on the body that receives irradiance from the source and emits irradiance having an initial intensity value toward the detector for detection which thereby identifies the cartridge as being suitable for use in that drive; and a matte material disposed between the marker and the body, the material receiving irradiance from the source.
According to one aspect of the present invention, the body comprises the matte material. According to another aspect of the present invention, the matte material is disposed within the marker, preferably mixed with the latent illuminance material.
According to other aspects of the present invention, the matte material has a substantially concave shape, and the latent illuminance material is disposed within the substantially concave shape of the matte material.
According to a farther aspect of the present invention, the latent illuminance material comprises a phosphorescent material.